Crystal structure and luminescence properties of a novel non-rare-earth activated blue-emitting garnet phosphor Ca4ZrGe3O12: Bi3+ for n-UV pumped light-emitting diodes

Abstract

A novel Bi3+ activated Ca4ZrGe3O12 phosphor was synthesized and the photoluminescence properties were investigated. Ca4ZrGe3O12:Bi3+ could be efficiently excited in the wavelength range of 320–430 nm, and exhibit a broad emission band (400–520 nm) with a peak at 435 nm corresponding to the 3P1–1S0 transition of Bi3+. Due to the energy transfer between Bi3+ ions, the concentration quenching in the Ca4ZrGe3O12 host occurred when the concentration of Bi3+ exceeded 2.25 mol %. Upon excitation at 370 nm, the internal quantum efficiency of the phosphor with different Bi3+ concentration was measured, the highest value was determined to be 38.6%. Moreover, the phosphor exhibited excellent thermal stability and the corresponding activation energy ΔE was determined to be 0.228 eV. Due to the efficient excitation in the near ultraviolet (n-UV) region and the strong blue emission, Ca4ZrGe3O12:Bi3+ would be a potential blue phosphor for n-UV pumped light-emitting diodes.